Smith–Purcell radiation-like photoacoustic phased array

Relativistic electrons moving over a periodic metal grating can lead to an intriguing emission of light, known as Smith–Purcell radiation [SPR), the precursor of the free-electron laser.The speed of light plays a critical role in the far-field emission spectrum. Inspired by this photonic SPR, here we experimentally demonstrate a photoacoustic phased array using laser-induced shock waves. We observe acoustic radiation spectrum in the far field, perfectly predicted by a universal theory for the SP...     

学生行为习惯矫正举措

本文通过对现代初中生行为习惯进行归纳其具体表现,并分析了形成这些习惯的具体原因来自于家长、社会、学校.根据这些原因找到了矫正的具体方法,通过这些方法的实施会让现代初中生的行为习惯有很大的转变.